1. Field of the Invention
The present invention relates to data coding and, in particular, to an improved method for compiling grammar extensions to data codes.
2. Description of the Related Art
The Abstract Syntax Notation One (ASN.1) is a notation for specifying data structures at a relatively high level of abstraction. In particular, ASN.1 defines a data structure protocol for describing messages to be exchanged between distributed computer systems. ASN.1 is used to generate programming language code that forms the core of a wide variety of massaging systems applications. For example, H.323 based systems use ASN.1 coded messages for signaling between H.323 endpoints, servers, gateways, and gatekeepers.
The ASN.1 language has evolved over time to include the ITU-T standards X.680 (Specification of Basic Notation), X.681 (Information Object Specifications), X.682 (Constraint Specification), and X.683 (Parameterization of ASN.1 Specifications), all of which are hereby incorporated by reference in their entireties as if fully set forth herein.
The basic ASN.1 compiler supports only X.680 grammar constructs. Typically, each extension has been supported through the development of an entirely new compiler. However, writing a compiler is relatively expensive and time consuming. Moreover, in certain instances, it is not possible because the code generated is proprietary. When new extensions of the grammar are defined, but the available compiler does not support them, the user cannot take advantage of the new features.
Typically, this has required the user to purchase a new compiler which, again, is relatively expensive. Alternatively, the user can manually convert the new grammar constructs into those that are supported by the old compiler.